1. Field of the Invention
The present invention relates to a stator for a rotary electrical machine that is, for example, mounted in a vehicle.
2. Description of the Related Art
As a stator for a rotary electrical machine, for example, as disclosed in U.S. Pat. No. 4,186,317, a stator is known that includes a ring-shaped stator core and a stator winding. The stator core has a plurality of slots arranged in a circumferential direction. The stator winding has a plurality of phase windings composed of a plurality of segment conductors that are disposed such as to be inserted into the slots and connected in series.
As shown in a connection diagram in FIG. 23B, each phase winding 143 configuring the stator winding is composed of a plurality of segment conductors 141 that are connected in series. As shown in FIG. 23A, the plurality of segment conductors 141 configuring a phase winding 143 of a single phase are disposed such as to be inserted into each slot 131 of the stator core 130. The plurality of segment conductors 141 are aligned in a radial direction. In this instance, the number of turns per slot is four.
JP-A-2002-27693 discloses a winding conductor for a rotary electrical machine. The winding conductor is inserted into the slots of a rotary electrical machine core. The winding conductor is composed of a plurality of wires that are compression-bonded to one another and press-molded to form a bundle that has a substantially rectangular cross-section.
In the rotary electrical machine disclosed in U.S. Pat. No. 4,186,317, as shown in FIG. 24, eddy current is generated within the segment conductors 141 as a result of leakage flux within the slot 131 interlinking with the segment conductors 141 configuring each phase winding 143 during energization of the stator. In particular, when the rotary electrical machine is being operated in a high-speed, high-torque load state, a large loss (alternating-current (AC) copper loss) occurs as a result of the eddy current. When the AC copper loss occurs in this way, problems occur in that the segment conductors 141 generate heat, a motor (rotary electrical machine) cannot be made smaller, and the like.
It is considered possible that the eddy current can be suppressed by the winding conductor disclosed in JP-A-2002-27693 being applied to the stator winding disclosed in U.S. Pat. No. 4,186,317. However, when the winding conductor disclosed in JP-A-2002-27693 is applied, problems occur in that the stator winding becomes significantly difficult to manufacture, cost significantly increases, and the like.